|  | 4.2 | Network Design Methodology
| 4.2.1 | Gathering and analyzing requirements
For a LAN to be effective and serve the needs of its users, it should be designed and implemented according to a planned series of systematic steps, which include the following: Gathering the users' requirements and expectations Analyzing requirements Designing the Layer 1, 2, and 3 LAN structure (that is, topology) Documenting the logical and physical network implementation The first step in designing a network should be to gather data about the organizational structure. This information includes the organization's history and current status, projected growth, operating policies and management procedures, office systems and procedures, and the viewpoints of the people who will be using the LAN. You need to answer the following questions: Who are the people who will be using the network? What is their level of skill, and what are their attitudes toward computers and computer applications? Answering these and similar questions will help determine how much training will be required and how many people will be needed to support the LAN. Ideally, the information gathering process helps clarify and identify the problems. You also need to determine whether there are documented policies in place. Has some data been declared mission critical? Have some operations been declared mission critical? (Mission-critical data and operations are those that are considered key to businesses, and access to them is critical to the business running on a daily basis.) What protocols are allowed on the network? Are only certain desktop hosts supported? Next, you should determine who in the organization has authority over addressing, naming, topology design, and configuration. Some companies have a central Management Information Systems (MIS) department that controls everything. Some companies have very small MIS departments and, therefore, must delegate authority to departments. Focus on identifying the resources and constraints of the organization. Organization resources that can affect the implementation of a new LAN system fall into two general categories: computer hardware/software and human resources. An organization's existing computer hardware and software must be documented, and projected hardware and software needs identified. How are these resources currently linked and shared? What financial resources does the organization have available? Documenting these types of things helps you estimate costs and develop a budget for the LAN. You should make sure you understand performance issues of any existing network.
| Threaded Case Study
Washington Project: Understanding the Customer

First and foremost, you must understand the customer. In the case of the Washington School District, you need to talk to major users of the network; find out their geographic location, their current applications; their plans for the future; and determine who the major players will be in helping you design the network. After you have gathered data on the district's organizational structure, you need to:

- Determine where information flows in the district
- Find out where shared data resides and who uses it
- Determine whether data outside the district-for example, data on the Internet-is accessed
- Define the issues or problems that need to be addressed

| Web Links
| Introduction to Network Design
| Internetwork Design Basics
| Designing Internetworks for Multimedia
| Dartmouth Method for Teaching Design